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PostPosted: Fri Oct 19, 2018 9:57 am 
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Joined: Fri Oct 19, 2018 9:17 am
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Location: guilford, VT, US
Read a forum message from 2011 about there being a dozen +/- fuses in these things...so far I can only find the 1 obvious
AC 30A and the pair of adjacent 3.0A 250V.
I have the owner's manual with schematic but lots to look at. Anyone know what Yamaha's symbol
for 'fuse' is, or where these puppies are located?
TY


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PostPosted: Fri Oct 19, 2018 10:02 am 
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Joined: Mon Aug 08, 2016 5:46 pm
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Location: Markham, ON, CA
Did you check here?

https://www.hifiengine.com/manual_libra ... 2040.shtml

If that does not tell you, you might have to take it apart. If you cannot tell what is a fuse or not, you best send it in to a trusted tech.


Last edited by brownslane on Fri Oct 19, 2018 10:04 am, edited 1 time in total.

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PostPosted: Fri Oct 19, 2018 10:04 am 
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Joined: Mon Apr 05, 2010 6:12 pm
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Location: Toronto, ON, CA
won't be a fuse issue
most likely an issue on the PCB


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PostPosted: Fri Oct 19, 2018 10:46 am 
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Joined: Wed Jul 23, 2008 5:04 pm
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Location: saskatoon, SK, CA
Where does the signal stop?

Could be as simple as a dirty switch or relay.
Relay still clicks? Give er a tappy tappy....

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PostPosted: Fri Oct 19, 2018 1:11 pm 
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Location: London, ON, CA
stim wrote:
Read a forum message from 2011 about there being a dozen +/- fuses in these things...so far I can only find the 1 obvious
AC 30A and the pair of adjacent 3.0A 250V.
I have the owner's manual with schematic but lots to look at. Anyone know what Yamaha's symbol
for 'fuse' is, or where these puppies are located?
TY

Typical fuse symbol.
Attachment:
fuse.png
fuse.png [ 2.31 KiB | Viewed 416 times ]

Possible cause of any destruction could be the 30A fuse...

Ohms

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PostPosted: Fri Oct 19, 2018 1:24 pm 
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Location: saskatoon, SK, CA
Hoping 3.0 and not 30. Otherwise....

Possible??? Probable...

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PostPosted: Fri Oct 19, 2018 2:43 pm 
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Joined: Fri Nov 18, 2011 6:41 am
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Location: Ottawa, ON, CA
Have a shop do it. It will take half the time and will have the correct one installed before you can turn another page in your manual to find out what going on.


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PostPosted: Fri Oct 19, 2018 7:56 pm 
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Location: Regina, SK, CA
stim wrote:
Read a forum message from 2011 about there being a dozen +/- fuses in these things...so far I can only find the 1 obvious
AC 30A and the pair of adjacent 3.0A 250V.
I have the owner's manual with schematic but lots to look at. Anyone know what Yamaha's symbol
for 'fuse' is, or where these puppies are located?
TY

The primary input power fuse is 10amp, the 2 x 3 amp you see are on the secondary side of the transformer, at 2 differnt voltage stages for various functions.
If the lights are out, primary fuse. (Or worse, deeper in the power supply/transformer)If the lights are on, its not a fuse problem. The other 2 smaller fuses would have to have blown independently to have a full sound outage.
The main fuse is tied directly in line... Power switch to backside receptacles, then the fuse and that is before the power transformer.
If you don't understand this, and I am being nice, do get it to someone who does know.
Quick check, is the outlet you have it plugged into ok?
When you say you 'found' a 30amp, do you mean a real 30 amp in the fuse holder inside? If so, this is a dangerous error someone made. It needs to remain as 10A..
If its blowing anything there 10 or 30, its a dead short, and way more complicated.
Its nearly 40 years old, much to consider.
Good luck.

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PostPosted: Fri Oct 19, 2018 8:37 pm 
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Location: Hamilton, ON, CA
May be the relay.

Channel drop outs, often after DeOxit fails, are often burnt/arc'd relays.
If you know where the relay is, and you are technically competent, you may want to try this first. After all, fuses just don't pop - if it did, you likely have another reason for the fuse failure and it will probably pop again when you replace it (assuming it's popped).

So, back to relays.
First and foremost, what is you technical competency? Do you know how to work safely with this sort of stuff? If you answer @ least a "7" out of 10 & a "yes" - continue on. IF not, bring it to a tech...

Assuming you are confident to further diagnose safely...Turn the unit off, unplug it.
Locate the relay, remove the clear plastic cover atop...,carefully (it's difficult to remove) - you may need a tool to help manipulate the plastic clips that hold the clear cover on. Use a non-conductive tool just to be safe. Work slowly to remove it or you will like break the clips or the cover, not a good start.
You can also remove the board with the relay if you don't have enough room & your feeling eager.

Once you have the clear plastic top off the relay, locate the relay contact points - inspect for pitting, burn marks, or oxidization. Take a business card, spray the business card with DeOxit. Soak the edge nicely, about a 1/8 of a inch along the length of it. Then, gently insert the edge of the card between the contact points on the relay and gently rock it back and forth, side to side. Remove the card and inspect it. You will likely see black on the card from oxidization. Once you feel it's been cleaned well and it's dried, place the cover back on the relay. At the same time, DeOxit all your controls one by one and rotate and rock switches one by one to help remove further oxidization. Clean up inside, don't leave contact cleaner all over the boards. I generally put a piece of cloth, papertowel, or a dry make-up pad under each switch before I clean it to soak up the leaking fluid. I use q-tips also to clean off excess from the switch or from the board.

Finally, turn on the unit - test for success. Once you've done this step, turn to checking the speaker outputs for DC. Get a multimeter, turn it to DC Volts in the autoranging setting. Let the amp "idle" with no signal, turn the input selector to a unused input, turn the volume down. After 10 mins, place your red probe from the multimeter in speaker A left channel (positive) terminal. Place the black probe in speaker A left channel (negative) - note your readings. You want to see like a 0.020 or less reading. Ideally, as close to zero as possible. Now do the same with the other speaker.

Assuming both channels are operating; this final test will help you understand the running condition of the amp. You are probably familiar with this, and that you don't want DC at the outputs. IF readings are over 50, it is in particular need of adjustment...it may be also a indication of internal capacitor condition. If you get a high reading 80-100+, you likely have a problem and audible distortion.

Now, assuming you don't have sound yet and you got a high reading, this may be also a indication of your problem.

If none of this made sense, don't play with the fuses or anything else. Bring it to the shop.


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